This invention relates generally to inserts for the finger holes of bowling balls and deals more particularly with inserts that act to improve the grip of the finger tip as well as to cushion it.
A prior art publication discloses a bowling ball insert which serves primarily to cushion the finger tip and does not enhance the grip to any appreciable extent. The surface of the insert which is gripped by the finger tip is a smooth surface which at most improves the grip only insignificantly. Also, the outside diameter of the finger insert can vary from unit to unit, and each insert can be used only in a finger hole that has been drilled to the particular size that will accommodate the insert. Thus, the drill holes in the bowling balls cannot be standardized in size. Another problem is that the wall thickness can vary depending on the size of the finger hole opening. When the wall contacted by the finger tip varies in thickness, the cushioning effect and "feel" vary from one insert to another, and there is a lack of uniformity in these respects. Variation in the thickness of the finger pad also makes it difficult to properly drill the finger holes to the proper span in the bowling ball, since the span or distance of the finger holes from the thumb hole is difficult to ascertain.
The present invention is directed to an improved bowling ball insert and has, as its principal goal, the provision of a finger insert which eliminates the foregoing problems. In accordance with the invention, a finger insert is held by partial vacuum in the finger hole of a bowling ball. A high friction corrugated surface on the finger pad area of the insert improves the grip of the finger tip and minimizes slipping of the bowling ball during delivery. The internal opening which receives the finger comes in a range of sizes so that the proper insert can be selected for each particular finger size. However, the outside diameter of each insert is the same regardless of the finger size so that all of the inserts fit interchangeably in standard size finger holes. This permits the finger holes of all bowling balls to be drilled to a uniform diameter. The thickness of the finger pad is the same for all of the inserts regardless of size, and uniformity is thus achieved in the cushioning effect provided by the inserts. Also, drilling of the finger holes in the bowling ball is facilitated because the span between the finger holes and thumb hole can be easily determined by subtracting the known and constant finger pad thickness from the measured span dimension. The finger openings for the smaller inserts are offset to one side in order maintain the strength of the bowling ball bridge. Due to the offset, the finger holes of smaller inserts do not have to be spread apart farther than those of larger inserts associated with larger hands.